According to changes in the broadcasting environment, a terrestrial broadcast is more likely to be provided to a user through retransmission using a set-top box instead of being provided to a user through terrestrial transmission.
When a terrestrial broadcast signal is retransmitted by using a set-top box or the like, a high-definition multimedia interface (HDMI), is mainly used as an interface between the set-top box and a television (TV). However, since the HDMI does not provide an interface for transmitting data other than audio data and video data, e.g., system data, system data may not be transmitted to the TV via the HDMI.
In this case, in order to use a bidirectional broadcasting service or a hybrid broadcasting service, a user must use a channel transmitted from a set-top box to a broadcasting company, and a TV is unable to function alone as a medium for bidirectional broadcasting.